Abstract: Hydroxyapatite (HA) whisker,with lower dislocation density and higher tensile strength,can be used as toughening material in bioceramic.HA whisker has been synthesized under hydrothermal condition by controling reaction temperature and time,using Ca (NO<SUB>3</SUB>)<SUB>2</SUB> &#8226;4H<SUB>2</SUB>O and (NH<SUB>4</SUB>)<SUB>2</SUB>HPO<SUB>4</SUB> as raw materials.The phases,morphology,size,and chemical composition of obtained products were characterized by X-ray diffraction (XRD),transmission electron microscope (TEM),and fourier transform infrared ray (FT-IR),respectively.The results showed that hydroxyapatite whiskers with high degree of crystallinity,uniform morphology,and with high slenderness ratio can be successfully synthesized by hydrothermal treatment with urea and sorbitol as addition agents,when n(Ca)/n(P) of precursors is 1.67.